The drive train of a conventional motor vehicle with an internal combustion engine as the sole drive source usually includes a starting component in the power flow between the drive source and the driving wheels in order to enable a starting process of the motor vehicle. One example of such a starting component is a hydrodynamic torque converter. The drive train of a motor vehicle with an electric motor as the sole drive source generally does not require a starting component, since the electric motor can accelerate the vehicle from a standstill.
The drive train of a parallel hybrid vehicle usually requires a starting component, provided a starting process is to take place also solely with the aid of the internal combustion engine. Different variants of the electric starting operation of a motor vehicle with a parallel hybrid drive train are known from the related art. Patent application DE 10 2006 018 058 A1 discloses different types of starting processes for a motor vehicle comprising a parallel hybrid drive train. Represented in FIG. 4 are time sequences during a purely electrically driven starting process with a torque converter lockup clutch in slip operation, and in FIG. 5 with an engaged torque converter lockup clutch.
Patent application DE 10 2016 206 742 A1 describes a method for selecting between a starting process of a motor vehicle with a parallel hybrid drive train with a slipping or a locked-up starting component depending on transmission-external parameters, and with a subsequent appropriate control of the torque converter lockup clutch.